postcss rgba mixins

const postcss = require('postcss'); // CSS to be processed var input = ` @mixin my-mixin($color: rgba(255, 255, 255, 0.6)) { color: $color; } .selector { @include my-mixin; @include my-mixin(#000); } `; // Process CSS const {css} = await postcss() .use(require('postcss-advanced-variables')) .process(input); console.log(css);